1. Field of the Invention
The present invention relates generally to extracting energy from a flowing fluid, and particularly to transferring the kinetic energy of a flowing fluid to a rotatable shaft.
2. Background Art
Devices such as windmills and wind generators have been used for many years to extract energy from the wind and use it to do work. For example, windmills have traditionally been used to pump water or turn a millstone. Wind generators are used to convert the mechanical (i.e., kinetic) energy of the wind to electrical energy. Both windmills and wind generators get their energy from wind blowing onto rotating blades that cause a shaft to rotate. In the applications described above, the rotating shaft is coupled to a mechanical device or an electrical generator.
The efficiency of prior art devices that use the wind's kinetic energy to do work is not very high. For example, in many configurations much of the wind flows past the blades without hitting them. Thus, a great deal of energy remains in the wind. In other configurations, the air flow is effectively blocked and the wind energy goes into the support structure instead of the drive mechanism. While many drive systems have been tried, each of the prior art systems has a low efficiency when it comes to extracting the wind's energy.